In recent years, demand has arisen for higher-accuracy control for a moving apparatus which moves with an object such as a structure placed on its stage. For example, with an exposure apparatus used for the manufacture of semiconductor devices, or the like, as the integration density of the semiconductor devices increases, a higher-accuracy micropatterning technique is demanded. In order to realize this, a moving apparatus, such as a wafer stage, must be controlled at a high accuracy.
Typical examples of an exposure apparatus used for the manufacture of semiconductor devices include a step-and-repeat exposure apparatus (to be referred to as a “stepper” hereinafter) and a step-and-scan exposure apparatus (to be referred to as a “scanner” hereinafter).
A stepper is an exposure apparatus that sequentially exposes the pattern of a master (e.g., a reticle, mask, or the like) onto a plurality of exposure regions on a substrate (e.g., a wafer, glass substrate, or the like), used for manufacturing semiconductor devices, through a projection optical system while stepping the substrate.
A scanner is an exposure apparatus that repeats exposure and transfer onto the plurality of regions on the substrate by repeating stepping and scanning exposure. The scanner limits exposure light with a slit, so that it uses that portion of a projection optical system which is relatively close to the optical axis. For this reason, generally, the scanner can expose a fine pattern with a wider angle of view at higher accuracy than with the stepper.
Such an exposure apparatus has a stage (e.g., a wafer stage, a reticle stage, or the like) for moving a wafer or reticle at a high speed. When the stage is driven, a reaction force of an inertial force accompanying acceleration and deceleration of the stage occurs. When the reaction force is transmitted to the stage surface plate, the stage surface plate swings or vibrates. Consequently, characteristic vibration is excited in the mechanical system of the exposure apparatus to generate high-frequency vibration. This vibration interferes with high-accuracy control for the moving apparatus.
To decrease the vibration of the apparatus caused by the reaction force, a moving apparatus as shown in FIG. 6 is proposed. As shown in FIG. 6, a conventional moving apparatus has a stage 51 and a movable body (to be referred to as a “counter” hereinafter) 52 for canceling the reaction force. The stage 51 and counter 52 are driven by feedback control controlling a position in the Y direction, and a target value is given such that the ratio of the moving distance of the stage 51 in the Y direction to that of the counter 52 in the Y direction is substantially constant. This improves the canceling efficiency for the reaction force of the stage 51.
With the conventional moving apparatus, however, as shown in FIG. 6, it is difficult to overlay the power point in the X direction of the stage 51 and the barycenter in the X direction of the counter 52 completely. Hence, due to the displacement in the X direction of the power point of the stage 51 and the barycenter of the counter 52, when the stage 51 moves in the Y direction, a moment is produced in the counter 52, and the counter 52 rotates. Therefore, with the conventional moving apparatus, it is difficult to control positioning of the stage at high accuracy.